We have our own stupid "bro language" with our friends
Just like a couple reaches a level in their relationship where a series of gestures and facial expressions are enough to convey what they're thinking, when men get together with their "boys," they devolve into their own language. Sometimes this consists of a series of, grunts and "Oh dude!"s, sometimes it's as complex as a conversation formulated entirely from classic Simpsons quotes. Some girls get really defensive when they find themselves trapped in a situation where the men around them suddenly start pointing to one another and yelling gibberish. Rest assured, we're not talking shit about you or purposefully leaving you out. Most likely, we're remembering the time one of our friends got drunk and started hitting on a tranny.
We all have a "secret girly thing"
As reluctant as we are to admit it, guys have at least one habit or interest that some would consider "girly." While most of us aren't going to get weekly pedicures, we are plucking our unibrows every now and then. That tough meathead pumping iron in the gym is probably listening to Lady Gaga on his iPod. That guy buying flowers at the grocery store might be getting them for his own apartment. Big or smallwe all have something. When you discover what it is, don't make fun of us. Or, actually, do make fun of us. Humor and mockery is our preferred method of dealing with most situations.
We're (almost) as insecure and sensitive as women
The general consensus seems to be that guys have to tip-toe around a woman's feelings, but that she doesn't have to extend the same courtesy. While men aren't as easily offended, we don't need you insulting our moms in the middle of a heated argument either. That goes for the converse. Women aren't the only ones who like positive reinforcement. Let us open a jar for you every now and then and we'll transform into the Incredible Hulk for a few minutes in our minds. Tell your boyfriend he's a stallion in bed even if he's more like a koala. Just because we don't bear our emotions as close to the surface doesn't mean we don't have them, and just because we don't outright ask for praise doesn't mean we won't revel in it.